Front unit for a sliding board binding, touring binding and ski-jumping binding

ABSTRACT

The present invention relates to a front unit ( 10 ) for a sliding board binding, comprising two engagement elements ( 32 L,  32 R), which comprise engagement portions ( 16 L,  16 R) which are set up so as to engage opposite lateral portions ( 14 L,  14 R) of a sliding board boot ( 12 ), the engagement elements ( 32 L,  32 R) being held pivotably on the front unit ( 10 ), and a tensioning means ( 34 ), which produces a resilient force for biasing the engagement portions ( 16 L,  16 R) in the engagement direction, the tensioning means ( 34 ) comprising a displaceably held tensioning element ( 40 ), the conversion between the pivoting movements of the engagement elements ( 32 L,  32 R) and the displacement movement of the tensioning element ( 40 ) being provided by way of a lever mechanism, which comprises: two levers which pivot in a manner corresponding to the engagement elements ( 32 L,  32 R), a displacement portion which is displaced in a manner corresponding to the tensioning element ( 40 ), and an articulation element ( 48 ), which comprises a first and a second pivot point at which it is pivotably connected to the levers and comprises a third pivot point, positioned between the first and the second pivot point, at which it is pivotably connected to the displacement portion.

The present invention relates to a front unit for a sliding board binding, comprising two engagement elements, which comprise engagement portions which are set up so as to engage opposite lateral portions of a sliding board boot, the engagement elements being held pivotably on the front unit, and a tensioning means, which produces a resilient force for biasing the engagement portions in the engagement direction, the tensioning means comprising a displaceably held tensioning element. The invention further relates to a touring binding and to a ski-jumping binding which are equipped with a front unit of this type.

A front unit of a sliding board binding generally has the purpose of holding a front portion of a sliding board boot on the sliding board, the sliding board binding generally further comprising a heel unit, which is responsible for fixing a heel portion of the boot. In downhill bindings, the lateral engagement elements are in the form of a left and right holding jaw, which engage around a tip of the sliding board boot and receive it between them, and which can be spread apart from one another by overcoming a spring force, in such a way that they release the boot in the case of a fall (releasing the binding). In ski-jumping bindings, touring bindings or cross-country bindings, the sliding board binding must be set up so as to release a heel portion of the sliding board boot, in such a way that it can lift off from the sliding board, whilst a front portion of the sliding board boot is held pivotably on the front unit about a pivot axis extending transverse to the longitudinal axis of the sliding board. For this purpose, the engagement elements of ski-jumping bindings and touring bindings comprise for example bearing means, which engage in complementary bearing means on opposite lateral front portions of the sliding board boot so as to form a rotary bearing. These bearing means are generally formed by projections which latch into corresponding depressions. In these bindings too, the engagement portions are biased into the engagement position with the sliding board boot, so as on the one hand to provide secure engagement of the bearing means and on the other hand to ensure emergency release of the binding.

Tensioning means of known front units use flat spiral springs to produce the necessary tensile force. Springs of this type have the advantage that they are hardly subject to any wear, can be produced cost-effectively, and have a well-defined force characteristic. However, since flat spiral springs have a linear movement characteristic, and thus act on a displaceably held tensioning element, movement conversion between the pivoting movements of the engagement elements and the displacement movement of the tensioning element is required. This is generally provided by a pivotable lever (for example of the engagement element) sliding against a linearly displaceably guided displacement element. It is inevitable that relatively high frictional forces will occur in the region of the contact between these elements, and this on the one hand accelerates the wear on the binding and on the other hand influences the release characteristic in a manner which is difficult to define. In addition, a linear guide for the displacement element is required, and involves a relatively high constructional expense and unavoidably entails further frictional losses. To reduce the wear and the frictional forces, it is thus always necessary in conventional bindings to encapsulate the movable parts using an additional housing and to protect them against the penetration of snow, ice and humidity.

Against this background, the object of the present invention is to provide a front unit for a sliding board binding, which is of a simple construction, operates with relatively low wear, and reduces frictional losses between the engagement elements and the tensioning element.

According to the invention, this object is achieved by a front unit for a sliding board binding, comprising two engagement elements, which comprise engagement portions which are set up so as to engage opposite lateral portions of a sliding board boot, the engagement elements being held pivotably on the front unit, and a tensioning means, which produces a resilient force for biasing the engagement portions in the engagement direction, the tensioning means comprising a displaceably held tensioning element, the conversion between the pivoting movements of the engagement elements and the displacement movement of the tensioning element being provided by way of a lever mechanism, which comprises: two levers which pivot in a manner corresponding to the engagement elements, a displacement portion which is displaced in a manner corresponding to the tensioning element, and an articulation element, which comprises a first and a second pivot point at which it is pivotably connected to the levers and comprises a third pivot point, positioned between the first and the second pivot point, at which third pivot point it is pivotably connected to the displacement portion.

At this point, it should be noted that in the context of the present disclosure, a sliding board is understood to mean any type of ski, snowboard or splitboard (snowboard which can be split in the longitudinal direction) or other board-like means for coupling to a boot and for moving along on snow and ice. In the context of the present disclosure, terms such as “up”, “down”, “lateral”, “forwards”, “backwards” or the like refer to a normal state of the front unit during use, in which normal state the front unit is mounted as intended on a sliding board, a sliding board boot of the user has entered the sliding board binding and is ready for travel, and the sliding board is positioned on a horizontal plane.

According to the invention, the conversion between the pivot movement of the engagement elements and the displacement movement of the tensioning element is provided by way of a lever mechanism, which transfers the pivot movement of two levers and the displacement movement of the tensioning element into one another by way of an articulation element, which comprises three pivot points arranged in a row for coupling the levers and the displacement portion.

The effect of the special arrangement of the pivot points on the articulation element is that the resulting lever mechanism always converts a pivot movement of the levers into a substantially linear movement of the displacement portion, and conversely a substantially linear displacement movement of the displacement portion is always converted into a pivot movement of the levers. In particular, this conversion results from the above-disclosed arrangement of the pivot points on the articulation element in relation to the levers and the displacement portion, and no linear guide is necessary for the displacement portion. The lever mechanism according to the present invention operates by the basic principle of a Watt linkage to convert the pivot movement of two levers, each articulated to fixed anchor points, into an approximately linear movement.

A major advantage resulting from the use of the lever mechanism according to the invention is that the movement can be converted entirely without the use of a linear guide and without the use of elements which slide against one another. Instead, the elements of the lever mechanism are mounted rotatably on one another at pivot points. Rotary bearings can be manufactured with outstanding force transmission properties and only small frictional losses. In addition, the bearing surfaces of rotary bearings generally overlap one another, in such a way that penetration of impurities, snow and moisture is obstructed, and these bearings thus exhibit lower wear than linear guides, cam mechanisms, control cam mechanisms or the like.

Preferably, the two levers of the lever mechanism are formed by the engagement elements themselves, that is to say the engagement elements are coupled directly to the first and second pivot point respectively of the articulation element, in such a way that the lever mechanism according to the invention can be manufactured with a small number of parts.

In a preferred embodiment of the invention, the engagement elements are held pivotably about a vertical axis (Z-axis), in such a way that the engagement elements can be mounted with a smaller construction height above the sliding board. The engagement elements can thus engage the front portion of a sliding board boot from the front in the manner of tongs.

In a further preferred embodiment of the invention, it is provided that each of the two engagement elements is pivotably mounted on a bearing portion on the front unit, and comprises a first lever arm extending from the bearing portion to the engagement portion and a second lever arm extending from the bearing portion to the articulation element. This makes it possible to position the articulation element at a suitable position in front of the sliding board boot, in that the second lever arm is constructed with a corresponding length and at a corresponding angle to the first lever arm. Engagement elements of this type may in particular be of an L shape, and the second lever arms may point towards a central longitudinal axis of the front unit. A construction of this type makes it possible to arrange the articulation element substantially in the region of the central longitudinal axis of the sliding board, and in particular also to displace the displacement portion substantially in the longitudinal direction of the sliding board, in such a way that effective use can be made of the construction space available on the sliding board.

The displacement portion of the lever mechanism may preferably be formed on the tensioning element, in such a way that the displacement movement of the displacement portion, produced or demanded by the lever mechanism, can be used directly for the movement of the tensioning means without further movement transmission, and thus results in a simpler construction of the front unit.

The tensioning means for biasing the engagement portions may comprise a spring means, which is braced against the tensioning element, in such a way that the resilient force can be transmitted directly to the displaceably arranged tensioning element, in particular by way of a spring element having a linear movement characteristic. The spring means may thus be braced on the one hand against the tensioning element and on the other hand against a spring bearing, which is rigidly fixed to the sliding board. In this context, the tensioning element may penetrate a clearance in the spring bearing, in such a way that the tensioning element can be displaced in the clearance and can thus be arranged in a compact manner. Preferably, the tensioning element may furthermore also penetrate the spring means, in such a way that the required constructional space on the sliding board can be further reduced.

In a preferred embodiment of the invention, the front unit further comprises an actuation element which is manually operable by the user, for moving the engagement portions between an engagement position, in which the engagement portions hold a sliding board boot in engagement, and an opening position, in which the engagement portions release the sliding board boot. With an actuation element of this type, which is to be operated manually and can be operated by the user for example by hand or using a ski pole, it is thus possible for example to move the engagement portions into an opening position before entering the binding, that is to say in particular to move them sufficiently far away from one another that the sliding board boot can be positioned between the engagement portions. Moreover, an actuation element of this type may be set up so as to make it possible to exit the binding in that the engagement portions are brought into the opening position by manually operating the actuation element. In variants of the invention, the transition from the opening position into the engagement position may also be provided by manually operating the actuation element, for example by operating it in the opposite direction in comparison with the operation for adjustment in the opening direction. Preferably, the front unit may comprise an entry mechanism for simpler and more rapid use, which mechanism, upon entry into the binding, brings about in part or completely automatic adjustment of the front unit from the opening position into the engagement position by exerting a contact force from the sliding board boot on the front unit. Overall, the technical effect of the aforementioned actuation element may be to move the elements of the front unit, which are relatively strongly biased, in particular the engagement elements and the elements of the lever mechanism, between the engagement position and the opening position by way of the actuation element, with a suitable force amplification or lever effect, in such a way that comfortable operation of the front unit is made possible.

In a front unit which is equipped with an above-described manually operable actuation unit, it may particularly advantageously be provided that the actuation element is pivotably coupled to a portion, which is rigidly fixed to a sliding board, of the front unit at a first actuation pivot axis, that the actuation element is pivotably coupled to an actuation member at a second actuation pivot axis, and that the actuation member is pivotably connected to an element of the lever mechanism, to one of the engagement elements or to the tensioning element at a third actuation pivot axis, the second actuation pivot axis passing a dead position, in which it intersects a connecting line between the first actuation pivot axis and the third actuation pivot axis, when the actuation element moves between the engagement position and the opening position. As a result of an arrangement of this type, the resilient force produced by the tensioning means can be used not only for biasing the engagement portions, but also for reliably locking the actuation element, specifically both in the opening position and in the engagement position. In both positions, the actuation element is held securely by the force, the direction of the action of the force (towards the opening position or towards the engagement position) being reversed at the dead point.

The invention further relates to a touring binding comprising a front unit of the above-disclosed type according to the invention. In touring bindings, reducing the weight and constructional size of the front unit is of particular importance, and so the simple and light construction of the front unit according to the invention achieves particular advantages in bindings of this type. In addition, touring bindings are subjected to particularly high reciprocated loads during ascent and subsequent descent, in such a way that the low-wear movement properties of the bindings according to the invention, which movement properties are well-defined as a result of the low friction, can be made use of particularly advantageously in this context during the frequent change between the engagement position and the opening position. In this context, touring bindings are particularly conceivable which comprise engagement portions comprising a projecting coupling journal in each case, the coupling journals of the two engagement portions facing towards one another. By using this coupling principle which is known per se, touring boots which comprise corresponding engagement holes in each case on opposite sides in the front sole portion can be coupled to the front unit.

In accordance with a further aspect, the present invention relates to a ski-jumping binding comprising a front unit of the above-disclosed type. In ski-jumping, the mechanical properties and functional characteristics of the sliding board binding take on particular importance, which is due to the competitive nature and inherent danger of this type of sport. The reliability of the sliding board binding, as well as the precision with which an engagement state between the boot and the binding and a release behaviour of the binding in the event of a fall are defined, are thus of decisive importance for competition success and for the safety of the ski-jumper.

The advantages highlighted above of front units according to the invention thus come into effect particularly clearly in a ski-jumping binding comprising a front unit of this type. Thus, by way of the lever mechanism according to the invention, which basically only comprises pivot bearings and thus operates with very low friction and wear, the engagement force with which the engagement portions hold the boot in place are defined and set very precisely, in such a way that on the one hand it is ensured that the ski is held securely on the boot during the flight phase and also when landing from a great height, and on the other hand release of the binding and decoupling of the ski from the boot can be ensured in the event of a fall.

Ski-jumping bindings of the aforementioned type may in particular comprise engagement portions comprising a coupling clearance in each case for receiving a coupling projection, which projects laterally from a front portion of a ski-jumping boot, in such a way that the coupling principle which is known per se can be used for the ski-jumping binding according to the invention for pivotably mounting the ski-jumping ski. When a front unit of this type is released, the forces acting on the binding of the boot urge the coupling projections out of the respective coupling clearances, the engagement portions being spread apart counter to the spring force of the tensioning means.

In the following, the invention is described in greater detail by way of preferred embodiments, with reference to the appended drawings, in which:

FIG. 1 is a perspective view of a front unit in accordance with a first embodiment of the present invention in an engagement position,

FIG. 2 is a perspective view of the front unit shown in FIG. 1 in an opening position,

FIG. 3 is a plan view of the front unit shown in FIG. 1 in an engagement position,

FIG. 4 is a plan view of the front unit shown in FIG. 1 in the opening position, and

FIG. 5 is a perspective view of a front unit in accordance with a second embodiment of the invention.

A front unit in accordance with the first embodiment of the invention, denoted generally as 10, is part of a ski-jumping binding, with which a ski boot 12 is held on a ski-jumping ski (not shown). In a manner known per se, the engagement between the boot 12 and the front unit 10 can be provided by way of lateral projections 14L, 14R, which engage in associated clearances 16L, 16R of the front unit 10. The projections 14L, 14R engage rotatably in the clearances 16L, 16R respectively, the two rotary bearings having a shared axis of rotation which is directed along a transverse axis Q extending transverse to a longitudinal axis L of the ski. In this way, the boot 12 is pivotably mounted on the front unit 10 about the transverse axis Q.

As is known per se for binding systems for ski-jumping, the projections 14L, 14R of the boot 12 may be spherical, so as to engage in recesses 16L, 16R of a corresponding ball socket shape in the front unit 10 (FIGS. 2 and 4). Preferably, the projections 14L, 14R are formed by opposite ends of a rod 18, which is fastened along the transverse axis Q to a projecting sole portion 20 of the boot 12, in particular laid in a groove 22 of the sole portion 20 and fixed to the sole portion 20 by means of screws 24, rivets or the like.

The front unit 10 may comprise a base body 26, which is to be fastened to a ski (not shown) by means of suitable fastening means, in particular screws 28. The base body 26, by way of the configuration of the fastening means thereof for mounting on the ski, defines a plane of the ski, in relation to which a Z direction pointing vertically upwards from the plane of the ski, an X direction extending parallel to the plane of the ski in the direction of the longitudinal axis L of the ski, and a Y direction extending orthogonal to the X direction and the Z direction are defined.

In the embodiment, the base body 26 comprises a left bearing portion 30L, on which a left engagement lever 32L is pivotably mounted, and comprises a right bearing portion 30R, on which a right engagement lever 32R is pivotably mounted. A left boot engagement portion, in this case formed by the left clearance 16L, is provided on the left engagement lever 32L, whilst a right boot engagement portion, in this case formed by the right clearance 16R, is provided on the right engagement lever 32R. The engagement levers 32L, 32R are pivotably mounted on the bearing portions 30L, 30R, in such a way that the clearances 16L, 16R can move towards or away from one another. A pivot axis S₁ of the left engagement lever 32L on the left bearing portion 30L and a pivot axis S₂ of the right engagement lever 32R on the right bearing portion 30R preferably point in the Z direction, that is to say vertically upwards.

The front unit 10 further comprises a tensioning means 34, which produces a resilient force for biasing the clearances 16L, 16R in the engagement direction, that is to say towards the boot 12. The resilient force is produced by a spring means 36, preferably a flat spiral spring, which is braced on the one hand against a spring bearing 38, which bearing is rigidly fixed to the base body 26, and on the other hand against a tensioning element 40, which is held displaceably with respect to the base body 26. In this context, the tensioning element preferably comprises a rod portion 42 and a head portion 44 which is fastened to or formed on the end of the rod portion 42. The rod portion 42 is preferably passed through the spring bearing 38 through a clearance (not shown) in the spring bearing 38 in such a way that the tensioning element 40 can be displaced along the axis of the rod portion 42.

At an end remote from the head portion 44, the rod portion 42 preferably carries a spring stop 46, against which the spring means 36 is braced. The spring stop 46 may particularly preferably be adjustable in the position thereof on the rod portion 42, for example comprising an internal thread which is engaged with an external thread of the rod portion 42, in such a way that a bias of the spring means 36 can be adjusted by rotating the spring stop 46. It can further be seen from the drawings that the rod portion 42 can penetrate the spring means 36 in the axial direction. If the rod portion 42 thus passes through both the spring means 36 and the spring bearing 38, the spring means 36 can be braced against the spring bearing 38, for example against an inner annular shoulder of a stepped hole in the spring bearing 38, or be held in an annular groove of the spring bearing 38.

The spring means 36 has a linear movement characteristic, that is to say the tensioning element 40 which is loaded by the spring means 36 moves back and forth in a substantially linear direction. The conversion between this displacement movement and the pivoting movement of the engagement levers 32 is provided by using a lever mechanism which operates by the same principle as a Watt linkage. The lever mechanism comprises an articulation element 48, on which the left engagement lever 32L is pivotably mounted about a pivot axis S₄, the right engagement lever 32R is pivotably mounted about a pivot axis S₅, and the tensioning element 40, in particular the head portion 44 of the tensioning element 40, is pivotably mounted about a pivot axis S₆. The pivot axes S₄, S₅ and S₆ are distinct from one another, extend mutually parallel and are preferably in substantially the same plane. In other words, a pivot bearing 50 (pivot point), at which the left engagement lever 32L is mounted on the articulation element 48, a pivot bearing 52 (pivot point), at which the tensioning element 40 is mounted on the articulation element 48, and a pivot bearing 54 (pivot point), at which the right engagement lever 32R is mounted on the articulation element 48, are arranged in a row on the articulation element 48, the pivot bearing 52 for the tensioning element 40 being arranged between the two other pivot bearings 50, 54, in particular in the centre directly between the pivot bearings 50, 54. Preferably, the three pivot axes S₄, S₅ and S₆ extend in the Z direction.

The articulation element 48 may comprise two plate portions 56, 58 which extend mutually parallel, for receiving the engagement levers 32L, 32R between them, in such a way that in particular bearing axes (only a bearing axis 60 of the right engagement lever 32R is shown in the drawings) of the engagement levers 32L, 32R can be mounted or held stably on both sides of the engagement levers 32L, 32R in the plate portions 56, 58. Further, in the embodiment, the head portion 44 is formed in the manner of a fork and comprises two plate portions 62, 64, which extend mutually parallel and between which the articulation element 48 can be received and pivotably mounted at the pivot point 52. The fork-like head portion 44 thus engages around the articulation element 48 and, as a function of the rotational position of the articulation element 48, optionally also engages around one of the two engagement levers 32L, 32R in part (in this case an end of the left engagement lever 32L at the pivot point 50). The fork-like head portion also makes stable mounting on the second pivot point 52 possible, in particular whilst preventing one-sided mounting.

The front unit 10 of the illustrated embodiment further comprises an actuation mechanism 66 for adjusting the front unit 10 between an opening position and an engagement position. The actuation mechanism 66 comprises a manually operable actuation element 68 in the form of a lever, which is pivotably mounted about a pivot axis S₇ on the base body 26 or on a part which is rigidly connected to the base body 26. In the embodiment, the actuation element 68 is articulated to the spring bearing 38 and the pivot axis preferably extends in the Y-direction.

The actuation element 68 acts directly or indirectly on movable parts of the front unit 10, in such a way that the clearances 16L, 16R are moved towards or away from one another in a manner corresponding to the movement of the actuation element 68. In particular, the actuation element 68 is pivotably connected at a pivot axis S₈, to an actuation member 70, which is in turn connected, so as to be pivotable about a pivot axis S₉, to the tensioning element 40, in this case in particular to the head portion 44. In this context, the pivot axis S₈ is positioned between the pivot axis S₇ and the pivot axis S₉, and, as a function of the position of the actuation element 68, can pass through a dead point (dead position), in which the pivot axis S₈ is positioned directly on a connecting line between the pivot axes S₇ and S₉, that is to say in particular all three pivot axes S₇, S₈ and S₉ are arranged in a shared plane. The dead point is a labile position, in such a way that outside this dead point the pivot axis S₈ is urged away from the dead point by the force of the spring means 36. The actuation element 68 can thus be moved into two different stable positions on either side of the dead point and locked there by virtue of the spring means 36.

In the following, a mode of functioning and operation of the front unit 10 in accordance with the embodiment of the invention will be described in greater detail.

FIGS. 1 and 3 show an engagement position of the front unit 10, in which the clearances 16L, 16R are moved sufficiently far towards one another that a ski boot 12 can be held securely engaged with the binding 10. This state is the normal operating state during ski-jumping. By contrast, FIGS. 2 and 4 show an opening state of the front unit 10, in which the clearances 16L, 16R are pivoted sufficiently far away from one another that the ski boot 12 is released from the engagement with the front unit 10. The front unit 10 is in this position in particular before entry into the binding and after exiting from the binding.

The adjustment between the engagement position and the opening position can be provided by manually operating the actuation element 68 (manually opening and closing the front unit 10). For this purpose, in the embodiment the actuation element 68 can be lifted out of the position shown in FIGS. 1 and 3 and pulled towards the boot 12, resulting in the head portion 44 of the tensioning element 40 being urged towards the boot by way of the movement of the actuation member 70. During this movement, the spring means 36 is compressed, in such a way that the operation of the actuation element 68 counteracts the force of the spring means 36 until the dead point of the pivot axis S₈ is reached. The displacement of the tensioning element 40 displaces the articulation element 48 which is held thereon, and pivots the engagement levers 32L, 32R, which are coupled to the articulation element 48, in such a way that the clearances 16L, 16R move away from one another. After passing through the dead point, the tensioning element 40 moves a little in the opposite direction again, that is to say away from the boot 12, this movement corresponding to the force action direction of the spring means 36, in such a way that the actuation element 68 is also moved further by the force of the spring means 36, until it is stopped by a stop (opening position). In the embodiment, the stop is provided between the actuation element 68 and the actuation member 70, that is to say a pivot angle between the actuation element 68 and the actuation member 70 is defined on one side by contact between the two parts. In this context, the stop is selected in such a way that, in spite of the slight return movement of the tensioning element 40 after passing through the dead point, the distance between the clearances 16L, 16R of the engagement levers 32L, 32R is still sufficiently large for releasing the boot 12 or for making it possible to insert the boot 12 between the clearances 16L, 16R.

For adjusting the front unit 10 from the opening position into the engagement position, the actuation element 68 can be moved in the opposite direction, in such a way that, in the embodiment, it is pivoted downwards towards the sliding board (away from the ski boot 12). After passing through the dead position, the spring means 36 acts to assist this pivot movement again, and urges the actuation element 68 further towards the engagement position, until it is stopped against a suitable stop, in this case for example on the tensioning element 40. As a result of the force of the spring means 36, the actuation element 68 is subsequently pressed securely against this stop, and the engagement position is thus locked.

During the aforementioned adjustment of the front unit 10, the force is basically only transferred at rotary bearing portions, that is to say in particular at the pivot axes S₁ to S₉. As a result of the particular movement geometry of the elements which are arranged in accordance with the model of a Watt linkage, the pivot movement of the engagement lever 32L, 32R is inevitably converted into a substantially linear displacement movement of the tensioning element 40, without a special linear guide or the like being necessary for this purpose. In particular, the tensioning element 40 does penetrate the spring bearing 38, but no guide or engagement is provided at this position. The rod portion 42 can penetrate the spring bearing 38, in particular with a large play, and move through it virtually without contact throughout the operation. The risk of a linearly movable element tilting in a guide and the occurrence of frictional losses can thus be prevented.

As a result of the above-disclosed arrangement in accordance with the embodiment of the invention, in the engagement position, the clearances 16L, 16R are biased towards one another by the force of the spring means 36, so as to hold the boot 12 securely engaged. On the other hand, however, this means that when overcoming a predetermined release force, which is exerted by the boot 12, for example during a fall, on the clearances 16L, 16R, the clearances 16L, 16R yield and can be urged away from one another counter to the force of the spring means 36. The boot 12 can subsequently be released from the front unit 10, so as to prevent injuries to the sportsman.

On the one hand, this release process can be influenced by setting the bias of the spring means 36, in particular by adjusting the spring stop 46. However, the contours of the recesses 16L, 16R and the contours of the projections 14L, 14R associated therewith of the boot 12 also further have an effect on the release characteristics. It can be seen in particular from FIG. 2 that the hollow depressions of the clearances 16L, 16R may have escape grooves 72 on an edge at the free end of the engagement levers 32L, 32R, that is to say the recesses 16L, 16R have a notched edge in the region of these escape grooves 72, in such a way that the projections 14L, 14R on the escape grooves 72 can slide out of the clearances 16L, 16R more or less easily as a function of the depth of the escape grooves 72. By specifying the direction of the escape grooves 72 in relation to the centre of the clearances 16L, 16R, a preferred release direction can further be specified. In the embodiment, the release is thus preferably parallel to the plane of the ski, and this corresponds to an Mz release, that is to say a release when the boot 12 is rotated about an axis in the Z direction.

FIG. 5 shows a second embodiment of the present invention, in which a front unit 110 is formed as a front unit of a touring ski binding. Accordingly, engagement portions 116L, 116R may comprise inwardly projecting journals 174L, 174R for pivotably holding a touring ski boot, in particular journals having conically tapering tips, which can engage in corresponding lateral openings 176 on a front portion of a touring ski boot 112. All remaining elements of the front unit 110 preferably correspond to the respective elements and functions of the first embodiment disclosed with reference to FIGS. 1 to 4, and are therefore not described again in the following. In other words, the second embodiment only differs from the first embodiment in the above-disclosed configuration of the engagement portions 116L, 116R.

It should be added that in the above-disclosed embodiments, in particular the force-transmitting bearings of the front unit on the axes of rotation S₁, S₂, S₄ to S₉ may in principle be implemented using any types of rotary bearings known to the person skilled in the art. Preferably cylinder bearings are used, which only make rotation possible about one axis of rotation. Bearings of this type may be formed in a cost-effective and low-wear manner as pin bearings, in which a bearing pin, provided with a corresponding coating or lubrication on an outer cylinder surface, is rotatably mounted in a matching bearing hole. 

1. Front unit for a sliding board binding, comprising two engagement elements, which comprise engagement portions which are set up so as to engage opposite lateral portions of a sliding board boot, the engagement elements being held pivotably on the front unit, a tensioning means, which produces a resilient force for biasing the engagement portions in the engagement direction, the tensioning means comprising a displaceably held tensioning element, characterised in that the conversion between the pivoting movements of the engagement elements and the displacement movement of the tensioning element is provided by way of a lever mechanism, which comprises: two levers which pivot in a manner corresponding to the engagement elements, a displacement portion which is displaced in a manner corresponding to the tensioning element, and an articulation element, which comprises a first and a second pivot point at which it is pivotably connected to the levers and comprises a third pivot point, positioned between the first and the second pivot point, at which it is pivotably connected to the displacement portion.
 2. Front unit according to claim 1, characterised in that the two levers of the lever mechanism are formed by the engagement elements.
 3. Front unit according to claim 1, characterised in that the engagement elements are held pivotably about a vertical axis.
 4. Front unit according to claim 1, characterised in that each of the two engagement elements is pivotably mounted on a bearing portion on the front unit, and comprises a first lever arm extending from the bearing portion to the engagement portion and a second lever arm extending from the bearing portion to the articulation element.
 5. Front unit according to claim 4, characterised in that the second lever arms of the engagement elements point towards a central longitudinal axis of the front unit.
 6. Front unit according to claim 1, characterised in that the displacement portion is formed on the tensioning element.
 7. Front unit according to claim 1, characterised by a spring means which is braced against the tensioning element.
 8. Front unit according to claim 1, characterised by a spring means which is braced on the one hand against the tensioning element and on the other hand against a spring bearing, which is rigidly fixed to the sliding board, the tensioning element penetrating a clearance of the spring bearing, and preferably further also the spring means.
 9. Front unit according to claim 1, characterised by an actuation element which is manually operable by the user, for moving the engagement portions between an engagement position, in which the engagement portions hold a sliding board boot in engagement, and an opening position, in which the engagement portions release the sliding board boot.
 10. Front unit according to claim 9, characterised in that the actuation element is pivotably coupled to a portion, which is rigidly fixed to a sliding board, of the front unit at a first actuation pivot axis (S₇), in that the actuation element is pivotably coupled to an actuation member at a second actuation pivot axis (S₈), and in that the actuation member is pivotably connected to an element of the lever mechanism, to one of the engagement elements or to the tensioning element at a third actuation pivot axis (S₉), the second actuation pivot axis (S₈) passing a dead position, in which it intersects a connecting line between the first actuation pivot axis (S₇) and the third actuation pivot axis (S₉), when the actuation element moves between the engagement position and the opening position.
 11. Touring binding, comprising a front unit according to claim
 1. 12. Touring binding according to claim 11, characterised in that the engagement portions comprise a projecting coupling journal in each case, the coupling journals (174L, 174R) of the two engagement portions facing towards one another.
 13. Ski-jumping binding, comprising a front unit according to claim
 1. 14. Ski-jumping binding according to claim 13, characterised in that the engagement portions comprise a coupling clearance in each case for receiving a coupling projection, which projects laterally from a front portion of a ski-jumping boot. 